Soluble gp130 regulates prostate cancer invasion and progression in an interleukin-6 dependent and independent manner

Dynamic Soluble IL-6R/Soluble gp130 Ratio as a Potential Indicator for the Prostate Malignancy Phenotype-A Multicenter Case-Control Study

OBJECTIVE

Prostate tumors, if prostate cancer or adenoma, represent a major public health challenge. Progress in research on inflammation has revealed a connection between inflammation, immunity, and cancer. In this context, this study aimed to find IL-6 signaling systemic abnormalities in the inflammatory tumor microenvironment.

MATERIAL AND METHODS

This study was case-controlled, multicentered, and included 86 patients, 43 diagnosed with BPH and 43 diagnosed with PCa, between January 2019 and January 2020. The study group was homogenous and the studied parameters were IL-6 complex (IL-6, soluble receptor IL-6R, soluble glycoprotein gp130), acute phase proteins (C reactive protein-CRP, acid alpha1 glycoprotein-AGPA, ferritin, albumin, transferrin), and oxidative stress-associated variables (malondialdehyde-MDA, carbonylated protein-PCO, 8-hydroxy-deoxy guanosine-8-OHdG, total antioxidant status-bTAS).

RESULTS

The inflammatory microenvironment determined IL-6 signaling alterations (over-regulation of sIL-6R and suppression of sgp130 in PCa versus BPH), changes in acute phase reaction markers (increased serum levels of CRP, AGPA, ferritin, and decreased serum levels of albumin, transferrin) that were much more evident in PCa compared to BPH, an imbalance between macromolecular oxidative damage (MDA, PCO, 8-OHdG) and endogenous antioxidants (TAS) that was more accentuated in PCa compared with BPH, and a representative association between the sIL-6R/sgp130 ratio and inflammatory/oxidative stress-related factors only in PCa patients.

CONCLUSIONS

Our study reconfirms the anterior concept that IL-6 promotes prostatic tumorigenesis. In this study, we first demonstrated that a high sIL-6R/sgp130 ratio facilitates prostate malignancy.

The role of the interleukin (IL)-6/IL-6 receptor axis in cancer

Interleukin-6 (IL-6) is a pleiotropic cytokine that activates a classic signalling pathway upon binding to its membrane-bound receptor (IL-6R). Alternatively, IL-6 may 'trans-signal' in a manner that is facilitated by its binding to a soluble derivative of the IL-6 receptor (sIL-6R). Resultant signal transduction is, respectively, driven by the association of IL-6/IL-6R or IL-6/sIL-6R complex with the membrane-associated signal transducer, gp130 (Glycoprotein 130). Distinct JAK (Janus tyrosine kinase)/STAT (signal transducers and activators of transcription) and other signalling pathways are activated as a consequence. Of translational relevance, overexpression of IL-6 has been documented in several neoplastic disorders, including but not limited to colorectal, ovarian and breast cancer and several haematological malignancies. This review attempts to summarise our current understanding of the role of IL-6 in cancer development. In short, these studies have shown important roles for IL-6 signalling in tumour cell growth and survival, angiogenesis, immunomodulation of the tumour microenvironment, stromal cell activation, and ultimate disease progression. Given this background, we also consider the potential for therapeutic targeting of this system in cancer.

Drosophila Jak/STAT Signaling: Regulation and Relevance in Human Cancer and Metastasis

Over the past three-decades, Janus kinase (Jak) and signal transducer and activator of transcription (STAT) signaling has emerged as a paradigm to understand the involvement of signal transduction in development and disease pathology. At the molecular level, cytokines and interleukins steer Jak/STAT signaling to transcriptional regulation of target genes, which are involved in cell differentiation, migration, and proliferation. Jak/STAT signaling is involved in various types of blood cell disorders and cancers in humans, and its activation is associated with carcinomas that are more invasive or likely to become metastatic. Despite immense information regarding Jak/STAT regulation, the signaling network has numerous missing links, which is slowing the progress towards developing drug therapies. In mammals, many components act in this cascade, with substantial cross-talk with other signaling pathways. In Drosophila, there are fewer pathway components, which has enabled significant discoveries regarding well-conserved regulatory mechanisms. Work across species illustrates the relevance of these regulators in humans. In this review, we showcase fundamental Jak/STAT regulation mechanisms in blood cells, stem cells, and cell motility. We examine the functional relevance of key conserved regulators from Drosophila to human cancer stem cells and metastasis. Finally, we spotlight less characterized regulators of Drosophila Jak/STAT signaling, which stand as promising candidates to be investigated in cancer biology. These comparisons illustrate the value of using Drosophila as a model for uncovering the roles of Jak/STAT signaling and the molecular means by which the pathway is controlled.

Interleukin-6 and Interferon-α Signaling via JAK1-STAT Differentially Regulate Oncolytic versus Cytoprotective Antiviral States

Malignancy-induced alterations to cytokine signaling in tumor cells differentially regulate their interactions with the immune system and oncolytic viruses. The abundance of inflammatory cytokines in the tumor microenvironment suggests that such signaling plays key roles in tumor development and therapy efficacy. The JAK-STAT axis transduces signals of interleukin-6 (IL-6) and interferons (IFNs), mediates antiviral responses, and is frequently altered in prostate cancer (PCa) cells. However, how activation of JAK-STAT signaling with different cytokines regulates interactions between oncolytic viruses and PCa cells is not known. Here, we employ LNCaP PCa cells, expressing (or not) JAK1, activated (or not) with IFNs (α or γ) or IL-6, and infected with RNA viruses of different oncolytic potential (EHDV-TAU, hMPV-GFP, or HIV-GFP) to address this matter. We show that in JAK1-expressing cells, IL-6 sensitized PCa cells to viral cell death in the presence or absence of productive infection, with dependence on virus employed. Contrastingly, IFNα induced a cytoprotective antiviral state. Biochemical and genetic (knockout) analyses revealed dependency of antiviral state or cytoprotection on STAT1 or STAT2 activation, respectively. In IL-6-treated cells, STAT3 expression was required for anti-proliferative signaling. Quantitative proteomics (SILAC) revealed a core repertoire of antiviral IFN-stimulated genes, induced by IL-6 or IFNs. Oncolysis in the absence of productive infection, induced by IL-6, correlated with reduction in regulators of cell cycle and metabolism. These results call for matching the viral features of the oncolytic agent, the malignancy-induced genetic-epigenetic alterations to JAK/STAT signaling and the cytokine composition of the tumor microenvironment for efficient oncolytic virotherapy.

Diacerein-mediated inhibition of IL-6/IL-6R signaling induces apoptotic effects on breast cancer

Interleukin-6 (IL-6) signaling network has been implicated in oncogenic transformations making it attractive target for the discovery of novel cancer therapeutics. In this study, potent antiproliferative and apoptotic effect of diacerein were observed against breast cancer. In vitro apoptosis was induced by this drug in breast cancer cells as verified by increased sub-G1 population, LIVE/DEAD assay, cell cytotoxicity and presence of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells, as well as downregulation of antiapoptotic proteins Bcl-2 and Bcl-xL and upregulation of apoptotic protein Bax. In addition, apoptosis induction was found to be caspase dependent. Further molecular investigations indicated that diacerein instigated apoptosis was associated with inhibition of IL-6/IL-6R autocrine signaling axis. Suppression of STAT3, MAPK and Akt pathways were also observed as a consequence of diacerein-mediated upstream inhibition of IL-6/IL-6R. Fluorescence study and western blot analysis revealed cytosolic accumulation of STAT3 in diacerein-treated cells. The docking study showed diacerein/IL-6R interaction that was further validated by competitive binding assay and isothermal titration calorimetry. Most interestingly, it was found that diacerein considerably suppressed tumor growth in MDA-MB-231 xenograft model. The in vivo antitumor effect was correlated with decreased proliferation (Ki-67), increased apoptosis (TUNEL) and inhibition of IL-6/IL-6R-mediated STAT3, MAPK and Akt pathway in tumor remnants. Taken together, diacerein offered a novel blueprint for cancer therapy by hampering IL-6/IL-6R/STAT3/MAPK/Akt network.

Inflammation and prostate cancer: the role of interleukin 6 (IL-6)

Environmental and genetic aspects are reflected in the development of prostate cancer. In this context, there is growing evidence that chronic inflammation is involved in the regulation of cellular events in prostate carcinogenesis, including disruption of the immune response and regulation of the tumour microenvironment. One of the best surrogates of chronic inflammation in prostate cancer is interleukin 6 (IL-6). Serum IL-6 levels are elevated in patients with untreated metastatic or castration-resistant prostate cancer (CRPC) and correlate negatively with tumour survival and response to chemotherapy. Via multiple signal pathways including the Janus tyrosine family kinase (JAK)-signal transducer and activator of transcription (STAT) pathway, the extracellular signal-regulated kinase 1 and 2 (ERK1/2)-mitogen activated protein kinase (MAPK) pathway, and the phosphoinositide 3-kinase (PI3-K) pathway, IL-6 is able to promote prostate cancer cell proliferation and inhibit apoptosis in vitro and in vivo. IL-6 is associated with aggressive prostate cancer phenotype and may be involved in the metastatic process through regulation of epithelial-mesenchymal transition (EMT) and homing of cancer cells to the bone. A substantial body of evidence suggests that IL-6 plays a major role in the transition from hormone-dependent to CRPC, most notably through accessory activation of the androgen receptor. Collectively, these data have stimulated the development of agents targeting IL-6 signalling pathways. A chimeric anti-IL-6 monoclonal antibody has been tested in clinical trials, with mixed results.

Cell type specific interleukin-6 induced responses in tumor keratinocytes and stromal fibroblasts are essential for invasive growth

Interleukin-6 (IL-6) is one of the major inflammatory interleukins that has been linked to cancer progression. In our model for human skin squamous cell carcinoma (SCC), IL-6 expression is strongly upregulated upon progression from benign tumors to highly malignant, metastasizing SCCs. We now demonstrate that IL-6 promotes malignant and invasive tumor growth in human skin SCCs by inducing cell type specific cytokine profiles in tumor keratinocytes and stromal fibroblasts, activating the latter towards a tumor associated fibroblast (TAF) phenotype. In three-dimensional organotypic cocultures in vitro invasive growth of IL-6 overexpressing tumor keratinocytes, is associated with increased expression of matrix metalloproteinase-2 (MMP-2), MMP-14 and tissue inhibitor of metalloproteinases-2, and clearly depends on IL-6 activated fibroblasts. IL-6-induced secretion of monocyte chemotactic protein-1 (MCP-1) in tumor keratinocytes and of hepatocyte growth factor in fibroblasts is crucial for regulating expression and activation of MMP-2. This functional role of IL-6 is confirmed in vivo. Here MMP-14 and MMP-2 expression occur exclusively in surface transplants of IL-6 overexpressing keratinocytes and fibroblasts are identified as important source of MMP-2. Our data indicate that tumor keratinocytes derived IL-6 activates stromal fibroblasts towards a TAF phenotype, promoting tumor invasion via enhanced expression and activation of MMP-2.

IL-6/IL-6R as a potential key signaling pathway in prostate cancer development

Interleukin-6 (IL-6) is a pleiotropic cytokine involved in prostate regulation and in prostate cancer (PC) development/progression. IL-6 acts as a paracrine and autocrine growth stimulator in benign and tumor prostate cells. The levels of IL-6 and respective receptors are increased during prostate carcinogenesis and tumor progression. Several studies reported that increased serum and plasma IL-6 and soluble interleukin-6 receptor levels are associated with aggressiveness of the disease and are associated with a poor prognosis in PC patients. In PC treatment, patients diagnosed with advanced stages are frequently submitted to hormonal castration, although most patients will eventually fail this therapy and die from recurrent castration-resistant prostate cancer (CRPC). Therefore, it is important to understand the mechanisms involved in CRPC. Several pathways have been proposed to be involved in CRPC development, and their understanding will improve the way to more effective therapies. In fact, the prostate is known to be dependent, not exclusively, on androgens, but also on growth factors and cytokines. The signaling pathway mediated by IL-6 may be an alternative pathway in the CRPC phenotype acquisition and cancer progression, under androgen deprivation conditions. The principal goal of this review is to evaluate the role of IL-6 pathway signaling in human PC development and progression and discuss the interaction of this pathway with the androgen recepto pathway. Furthermore, we intend to evaluate the inclusion of IL-6 and its receptor levels as a putative new class of tumor biomarkers.The IL-6/IL-6R signaling pathway may be included as a putative molecular marker for aggressiveness in PC and it may be able to maintain tumor growth through the AR pathway under androgen-deprivation conditions. The importance of the IL-6/IL-6R pathway in regulation of PC cells makes it a good candidate for targeted therapy.